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Car Digital Voltage and Temperature Meter

By on February 6, 2015












volt temperature gauge

Two weeks ago, I called up a guy to install the Digital Voltage/Temperature meter (gauge) on my Nazaria car dashboard. The reason I install it is to monitor the Voltage and the Temperature reading in real time. This means if the battery, alternator, radiator or the fan and etc have problem, the meter will beep indicating there is a problem. Once you heard the beep sound, it is advisable to stop or park your car at the side for further checking or you can call up the mechanic to inspect your car.  This will prevent your car from further damage (especially the engine) or stall halfway in the middle of the road. This will save the cost of a heavy repair price. This meter was recommended by one of my former students. After two weeks of driving, here are the results that I’d got:

Temperature reading- Driving in the afternoon:

Normal driving (highway)- Temperature between 86 to 90 degree Celsius

Going uphill- Temperature can be between 92 to 98 degree Celsius (usually will come down again to about 94/95 once the fan kicks in)

Traffic Jam- Temperature between 90 to 94/95 degree Celsius

Note: This result is based on my country weather which is now at average 30 degree Celsius. In the morning where the temperature is a bit cooler the overall temperature measured would be slightly lower. If the reading keeps on increasing even after 98 degree Celcius (beeper will sound) this means there is a problem.

Voltage Reading

Before starting engine- About 11.7 to 12.3 Volt

Engine is running- About 13.7 to 13.9 volt (which means Alternator is running/charging)

Engine is running with Aircond, headlight and brake lights On- About 13.2 to 13.5 volt

Note: If you get less than 12.8 volt or more than 14.8 volt while the engine is running (without turning On the Aircond/Headlamp etc), it is time to send the car to mechanic for inspection especially the alternator. Below is the chart for car voltage reference:


Meter specification:

– over 98 Celcius -the beeper will sound

– Less than 10 volt- the beeper will sound

– Meter can be installed on big vehicles that uses 24 volt



Once you have understood the reading of your car (it can be installed on all kind of cars), you will know when to send it to mechanic for further checking.

If you are driving a new car then it is not necessary to install one but my car is already more than 5 years old and clocked 110,000 km! Last year July, after my training class at about 6pm, I could not start my car because the battery was totally flat (my car was using a maintenance free battery). Then on August the same year, one night while carrying my family on the way back home, the car started to jerk intermittently for just few minutes and then back to normal again. The next day in the morning, I could start the car with one try and thought it was fine. The problem started when I was half way to my office, it started to jerk again and this time there was no sign that the jerk will stop. I quickly drove my car to the nearby workshop and the moment it reached the workshop, the engine just went dead. Guess what the problem is?  It was a bad alternator!

The mechanic told me the alternator was not in good condition causing less charge to the battery. Once the battery power is drained by the Aircond dc blower fan/headlight/signal light/brake light and etc, and if the alternator have problem there would be no or not enough charge going back to the battery and the battery voltage will drop. If the battery voltage is too low, the “Engine Control Unit” ECU in the car would not function properly causing the car to jerk and stall.

Just imagine if I had the volt/temperature meter installed at that time, I would have driven straight to the mechanic instead to my office or outstation (worst scenario). With the information provided by the meter, you could prevent your car from breaking down in the middle of the road and saving money from calling a tow truck service or etc.

car temperature joint pipe

I spoke to my friends about this meter and two of them had a great interest on this meter. The first friend told me his wife was driving his car (my friend was not with her) and suddenly the water temperature went up and there was no alarm and she did not notice it. She only stops when she saw thick smoke (radiator steaming) coming out from the front bonnet. It was too late and my friend had to overhaul his car engine.

The second guy told me, his car already overhauled twice within 6 years due to engine overheating problem. By the time he noticed the car temperature went full swing, it is already too late.

I heard a story of another guy who told me his car was having problem in the middle of highway due to overheat problem. He let the car temperature to cool down before driving to the workshop. Eventually he still have to overhaul the engine because he found that his car efficiency was not like original anymore.

The real culprit (problem) is the original Naza ria car water temperature meter. Why? Let me ask you a question-“Do you always look at the car temperature all the time while driving?” I guess no. With this meter, it will beep once it exceeded to more than 98 degree Celcius but the car water temperature meter needle would still shows normal!!! This is the problem.

volts and temperature meter

Another good point of installing this meter is, it can let you know if the radiator and the cooling system have any leakage or not. This means if the reading of the temperature is say 50 or 60 degree Celcius (even after 20 minutes of driving) you would know that the water level is not touching the sensor and this indicates leakage in the radiator system.

The meter was installed by Mr Haris and he is a humble guy and if you are a local and wish to fix this meter you can email me and I will give to you his contact number. His labor/ transport charge plus fixing the meter with the sensor and water temperature joint pipe was about USD55.00 which I find it to be reasonable. If you stay far from his place (Jalan Kuching), he might charge a bit more for the extra mileage.

Conclusion- Since my car engine one of the common faults is overheat, after fixing this meter, I have confident in driving the car especially travelling long journey (holiday with family) and fishing trip with friends. I rather pay this amount then to regret later in overhaul the whole engine. If you have any comment/story about your car overheated engine or already have this kind of meter or other interesting meters installed in your car we would like to hear about your story.








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  1. Robert Calk

    February 6, 2015 at 1:06 pm

    Hi Mr. Yong,

    Sounds like a good idea. I have an added illuminated oil pressure gauge installed on my car. I can see real fast in case my engine loses oil pressure.

    • Jestine Yong

      February 6, 2015 at 1:22 pm

      HI Robert,
      That is another good meter that need to be installed.


  2. Lawrence Pina

    February 6, 2015 at 11:29 pm

    Did you consider a ScanGauge? They test everything, not just Water Temperature and Battery Voltage. They're also much easier to install. Just plug it into the car's OBDII port, stick on the dash with velcro, indicate the size of your engine and fuel tank and you're done. UltraGuage is also good.

    • Jestine Yong

      February 7, 2015 at 11:03 am

      Hi Lawrence,

      Wow! Thanks for the good info. Those are really good products. I'm not sure if the local mechanic here be able to install such gauge that involve in OBD. Perhaps got to check with them first.


  3. Amir Mukhtar

    February 7, 2015 at 1:42 am

    Sir, Jestine yong. Thanks you for your Great expert sharing articles.

    yours Student
    Amir Mukhtar AShrafi

  4. Lynn Blakely

    February 7, 2015 at 4:37 am

    Hi Mr. Young: Thanks for the article about the water temperature, and digital voltage meter. You are correct about this unit being a necessity as many autos have idiot lights on the dash. I am wondering if there are any distributors in the USA. One comment it would be nice if a sensor could be used at the radiator hose, so that a wire could be used to operate the sensor in the display. This would make the install less offensive as far as cosmetics are concerned.

    • Jestine Yong

      February 7, 2015 at 10:48 am

      HI Lynn,

      You can source one from ebay or aliexpress. They have different designs. As for the sensor, it is connected to a joint pipe of the radiator hose.


  5. moshe

    February 7, 2015 at 8:33 am

    that was an interesting article which made me think about an interesting issue i have with my car (an alfa romeo 2001).

    when i drive at night and switch on the high beam (normal headlights are already on) the electronic speedometer dips for about 1/4 sec...but the rev counter and the dash lights show no change. Similarly when i flick the headlights on i get the same thing happening.

    i know there is no connection between the speedometer circuit and the lights so i figure it has something to do with a lag in replenishing the additional current for the high beam lights by the alternator. So now i wonder where to search and what to search for...failing power FET? failing transistor?

    Any ideas?

    • Jestine Yong

      February 7, 2015 at 10:52 am

      Hi Moshe,

      I suggest that you send the car to the mechanic and tell him about the lag. I heard some have to add a relay to overcome such problem.


    • Robert Calk

      February 7, 2015 at 11:26 am

      Your alternator may not be outputting enough voltage.

      • moshe

        February 7, 2015 at 4:49 pm

        thanks for your suggestions.
        Jestine, previous experience with auto-electricians has not been good....but your gadget gives me an idea.

        Robert, interesting what you say. i think i will connect my multimeter to the battery and see whats happening whilst driving.

        • Robert Calk

          February 7, 2015 at 11:37 pm

          First, make sure your alternator & battery wiring connections are good, tight, and clean. Then start the engine and turn on the headlights & A/C. Measure the output of the alternator. If the voltage is lower than what it should be, then test the battery to make sure that it isn't the problem. If the battery is good, replace the alternator.

          • Jestine Yong

            February 8, 2015 at 3:54 pm

            HI Robert,

            One more thing to check on the alternator belt. If it is loosen then it not be able to charge up a battery efficiently.


          • Robert Calk

            February 8, 2015 at 11:46 pm

            Hi Mr. Yong,

            Yes, the belt needs to be good and tight. But they usually squeak when they are loose.

          • moshe

            February 9, 2015 at 12:29 pm

            the REALLY weird thing about this issue (its been going on for over 2 years now) is that it is ONLY the speedometer that is affected - rev counter, interior lights, radio, fan all remain constant.

      • Henrique Ulbrich - Brazil

        February 8, 2015 at 2:51 am

        If this is occurring (alternator not outputting enough voltage), you could have other types of problems before (engine not starting or other) due to flatness of battery. Moreover, if the battery is healthy, this battery would have to keep the voltage up this time, and this symptom would not occur.

  6. peter

    February 7, 2015 at 11:56 am

    The most common cause of engine failure has been established as "coolant loss".
    SO for arguments sake - if your top radiator hose fails (mine did) you loose coolant very rapidly & your normal temp gauge will not see any differenec & provide no warning!! Almost always terminal damage particularly so if your heads are of aluminium.
    Now does this instrument offer protection for this kind of failure by an immediate a loud warning?
    What is the brand, the specs & the cost.
    For those of us overseas (USA, UK, Australia etc) how can it be purchased?
    Finally the pic of the actual sensor installation looked a little questionable to me & I could not help but think it was one additional failure point. If it should fail at the point of installation - who pays?

    • Jestine Yong

      February 9, 2015 at 9:43 am

      HI Peter,

      This meter will not beep if the radiator hose fail but you will see from the temperature reading that it would not rise more than 50 or 60 degree Celcius. I'm not sure where the guy got it but from Google search just now I found this meter:

      As for the installation of the joint pipe between the two hose, the guy told me that many people had installed it themselves but eventually "leaked" due to that they did not put in the extra sealant. If you look at the photo of the joint pipe you could see the extra sealant at the side. He had installed the same device into his car (he had a same car with me) for more than 4 years and so far no problem. He advised me to check on all the hose, joint pipe, water level, engine oil and etc one in a while or before starting a long journey.


  7. Andre Gopee

    February 8, 2015 at 8:12 am

    Hi Jestine, Thanks for the great info. It sound like a really good idea.

    • Jestine Yong

      February 8, 2015 at 3:52 pm

      HI Andre,

      You are welcome!


  8. Dominic

    February 8, 2015 at 6:04 pm

    Hi.My name is Dominic. I do a lot of Electronics repair as a hobby but I mainly work day to day as a motor mechanic.From experience I can tell you that if temperature gauge on your car rises above 3/4 for any reason it could be very disastrous for engine perhaps needing expensive overhaul.If an engine is run for more than 2 minutes without oil & oil pressure it will seize with extensive damage & not even overhaul will be able to put right.A bad alternator is least worry but big inconvenience as it will only make car stop & all lights & accessories not work.

    • Jestine Yong

      February 9, 2015 at 9:24 am

      HI DominiC,

      Thanks for the input.


  9. Humberto

    February 11, 2015 at 1:35 am

    Great idea taking into consideration more instruments which can alert to the driver about any abnormal situation that can occur during the travel in a automobile.

  10. Florin

    February 11, 2015 at 3:41 pm

    Mr. Yong,
    The real problem is NOT the original car water temperature meter. It is the cheap thermostat that fails first. The manufacturer of the car is the second problem. They put a complex computer to monitor the engine operation, yet they don't find important to sound a buzzer if the water temperature is over 100C. Why? They do it on purpose. The engine will get destroyed from overheating and they will sell a new engine...

    • Jestine Yong

      February 12, 2015 at 5:03 pm

      Hi Florin,

      So many cars that had been hit by the engine overheating problem. They should have just install it to avoid unnecessary problem.


  11. Gary Gemmell

    February 12, 2015 at 6:16 am

    Hi Justine - you may want to try OBDII if your car supports this 2002 year+

    For just voltage you can use one of these plugged into cigarette lighter socket. Very cheap and very easy do it yourself.

    Or you can buy OBDII gadget - Shows all computer ECU system outputs - voltage, oil pressure , water temperature , accelaration , lambda sensor etc etc etc for £5 with smartphone attached to dashboard - Much cheaper , more information - Use smartphone application Torque!!!!

    • Jestine Yong

      February 14, 2015 at 2:11 pm

      HI Gary,

      I have got the first one but the second one I'm afraid my mechanic would not be able to use it. Try check out another latest tool:



  12. Larry Spencer

    June 28, 2015 at 2:09 am

    I have a 2013 Nissan Altima 3.5SV that I have been having "intermittent" problems since I drove it off the lot brand new. It has been to 2 different Nissan dealers and had 2 different Regional Techs look at the car. From the start, I have insisted some type of electrical problem ( transmission not shifting properly or shuddering like it is going to fall out of car). They have decided that I have to have a second transmission replaced, but this time the Tech actually listened to me and checked the charging system. He decided, upon inspection, that the alternator "might" not be working properly and he would replace it also. I have had electrical interference displayed in my backup camera display, the headlights have "blinked" off then back on, the front passenger airbag disabled light comes on when it's not supposed to, the satellite radio loses programming, and other electrical accessories "self-activate." As you said in your article, if the ECM (computer) in the vehicle doesn't get the correct voltage, the vehicle will not perform accordingly. Hopefully, this will be the last time my car sees the shop, except for routine maintenance!!!!

  13. 5zaft

    August 21, 2016 at 3:50 pm

    Does naza ria has obd2 port?
    I can't find any

    • Jestine Yong

      August 22, 2016 at 12:10 pm

      Hi Mohd,

      The friend who had installed the meter told me it has OBD II and it can be found between the battery and the head lamp. It uses 21 pins connector while other cars uses only 16 pins. Hope this helps.



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